Dynamic simulation and finite element analysis of the human mandible injury protected by polyvinyl alcohol sponge

There have been intensive efforts to find a suitable kinetic energy absorbing material for helmet and bulletproof vest design. Polyvinyl alcohol (PVA) sponge is currently in extensive use as scaffolding material for tissue engineering applications. PVA can also be employed instead of commonly use kinetic energy absorbing materials to increase the kinetic energy absorption capacity of current helmet and bulletproof vest materials owing to its excellent mechanical properties. In this study, a combined hexahedral finite element (FE) model is established to determine the potential protection ability of PVA sponge in controlling the level of injury for gunshot wounds to the human mandible. Digital computed tomography data for the human mandible are used to establish a three-dimensional FE model of the human mandible. The mechanism by which a gunshot injures the protected mandible by PVA sponge is dynamically simulated using the LS-DYNA code under two different shot angles. The stress distributions in different parts of the mandible and sponge after injury are also simulated. The modeling results regardless of shot angle reveal that the substantial amount of kinetic energy of the steel ball (67%) is absorbed by the PVA sponge and, consequently, injury severity of the mandible is significantly decreased. The highest energy loss (170 J) is observed for the impact at entry angle of 70°. The results suggest the application of the PVA sponge as an alternative reinforcement material in helmet and bulletproof vest design to absorb most of the impact energy and reduce the transmitted load.